M. Studer on the Geological Structure of the Alps. 195 



In no district, however, are the nummulitic limestone and 

 the macignos better developed than in the most northern 

 chain of the limestone Alps, which, traversing the cantons of 

 Apenzell, of Schwytz, and of Unterwalden, afterwards in- 

 cludes Mont Pilate, the Schratten, and the Hohgant. It is 

 this same chain which is prolonged to the west of the lake of 

 Thoune by the Gemmi, the Diablerets, and the Dent de 

 Morcles, beyond our frontiers to the Buet, and the mountain 

 of Fis, so celebrated for its fossils, and then across Savoy into 

 Dauphiny ; and in this prolongation, the inferior beds of chalk 

 can be more easily determined than in the interior of the 

 Alps, where they are generally very deficient in fossils. 



Seeven Limestone. — We find under the nummulitic limestone, 

 and sometimes replacing it, a thick limestone formation, which 

 has a character depending on the district, and forms the upper 

 part of the chains. In the cantons of Appenzell and of Schwytz, 

 M. Escher has given to this formation, which seems to be awant- 

 ing in a portion of Switzerland, the name of Calcaire de Seeven. 

 It is for the most part compact, of a grey or red colour, desti- 

 tute of organic remains, and contains thin undulating argil- 

 laceous lamina. The lower part of this deposit generally 

 forms those vast corroded and fantastically furrowed rocks, 

 which in Switzerland are known under the name of Karren- 

 felder, and in which we find numerous organic remains, espe- 

 cially dicerates, a particular species of hippurite {H. Blumen- 

 bachii), and some large gasteropods allied to the tornatella^. 

 It is probable that this division corresponds with the calcaire 

 a hippurites of the south of France. 



Glauconite. — Below this limestone occurs the bed with inoce- 

 rami, which frequently has a thickness of only a few fathoms, 

 but is remarkable for the quantity of fossils it contains, which 

 fossils are for the most part identical with the speciesof theP^/*^^ 

 du Bhone and the glauconite of Rouen.* The rock is a black- 

 ish siliceous limestone, filled with greenish grains, intimately 



* The most chai-acteristic of these fossils are, Inoceramvs concaitricvs, 

 Park. ; Inoceramus mlcatuf, Park. ; Anwwnitcs injlatus, Ammonites siibcris- 

 la(u?, Brong., Sow. ; Turrilites Bergeri, Brong. ; Trochus Gurgitis, Brong. . 

 Trochus cirroidis, Brong. ; Cassis Avellana, and Micrasto' minimu$f Ag. — K 



DESOlt. 



